This is when two male friends have reached a stage in their (non-gay) relationship that is so close and so amazing that they are no longer bromos but have joined eachother in a commitment of husbro and husbro. Until death do them apart. This is the final ultimate stage in any bromance.

The stages:

*Friends
*Buddies
*Bros
*Bromo (The start of the bromance, first coined by Scrubs in the bromance of J.D. and Turk)
*Husbro (First coined by Raul/Sandrock in his bromance with Xterm/Wizzy)

Hey did you hear about Harry and Ron they are becoming Husbros next week!
Wow, so they finally made the choice move from bromos to commit themselves as husbros? That's amazing news!